1. Field of the Invention
The present invention relates to a method of manufacturing ferulic acid which is used as a raw material of, for example, medicines, agricultural chemicals, cosmetics, pigments, and food additives.
2. Description of the Related Art
It is known that ferulic acid is manufactured by the condensation reaction of vanillin with malonic acid, as described in, for example, "Journal of the American Chemical Society, 74, 5346 (1952)". The condensation reaction certainly produces ferulic acid in a high yield. However, it takes as long as about three weeks to manufacture the product ferulic acid, making the known condensation method unsuitable for use in the commercial manufacture of ferulic acid, as described in, for example, "J.R. Johnson, Organic Reactions 1, 250 (1942)". In addition, the product ferulic acid is a mixture of trans- and cis-isomers. Under the circumstances, vigorous researches are being made in this technical field in an attempt to develop a method of manufacturing ferulic acid, which permits commercially manufacturing ferulic acid of high purity, i.e., ferulic acid which does not contain cis-isomer.
In the manufacture of rice salad oil, some by-products and waste materials are discharged, for example, a blackish brown waste oil having a high viscosity, an alkaline oil cake rich in oil components, which is called soap stock, and a by-product rich in crude fatty acids, which is called dark oil. These waste materials and by-products are known to contain useful components. However, it was customary for these waste materials and by-products to be disposed of as useless industrial waste materials by, for example, a burning treatment, because a technique for effectively utilizing these waste materials was unknown in this technical field.
The present inventors have investigated the components of the waste materials and the by-product noted above, and then have found by the chromatographic method that about 10 to 30% by weight of oryzanol is contained in the waste material or the by-product. Certainly, oryzanol itself is a useful component. However, since components other than oryzanol are contained in large amounts in these waste materials or the by-products, it is difficult to recover effectively oryzanol alone, leading to a high manufacturing cost of oryzanol. Thus, it is economically impossible to recover oryzanol from the industrial waste materials or the by-products noted above.